This invention relates to apparatus for treating objects in an enclosed compartment and particularly to a robot positioner for a media blasting 5 system of the type in which one or more workpieces are located within an enclosure and the workpiece is blasted by a media, such as silica glass, ejected by air from a blasting gun against the workpiece. This invention relates more particularly to the robot positioner and a ceiling means for retaining particles of the media within the enclosure while at the same time permitting the blasting gun to be manipulated along horizontal "X" and "Y" coordinates within the enclosure and the associated ceiling construction. This invention is applicable to any device which is to be movable within an enclosure and treat an object with a substance some of which is capable of escaping through an open top of the enclosure.
In the finishing of metallic parts, it has been a common practice to enclose the part in an enclosure in which is located a blasting gun which forces the blasting media by air against the workpiece. In this blasting operation, the force of the media striking the workpiece and the surrounding apparatus, such as the holder of the workpiece, causes some of the blasting media to break up into fine particles which are suspended in the atmosphere of the enclosure. These fine particles have a tendency to escape from the compartment in which the blasting is taking place unless the compartment is completely enclosed and sealed. Because of the dust located within the enclosure and the deleterious effect it will have on any apparatus for controlling the movement of the blasting gun, it is desirable that the means for moving the gun along the "X" and "Y" coordinates be located outside of the compartment or enclosure. The present invention relates to such a manipulator.